<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>作业7</title>
</head>
<body>
<script>
  var str="";
  for (let i = 0; i < 4; i++) {
      for (let j = 0; j < 5; j++) {
          str+="*";
      }
      str+="\n";
  }
  console.log(str);
</script>
</body>
</html>